Arylfluorophosphate Inhibitors of Intestinal Apical Membrane Sodium/Phosphate Co-Transport

ABSTRACT

The present invention is directed to fluorophosphates, and pharmaceutical compositions thereof, which are inhibitors of intestinal apical sodium/phosphate co-transport and are useful in the treatment of hyperphosphatemia, in reducing blood phosphate levels, and in treating hypertension.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Application No. 61/310,902, which was filed Mar. 5, 2010.

FIELD OF THE INVENTION

This invention relates to hydrophilic aryl fluorophosphates that act toinhibit intestinal apical membrane Na-mediated phosphate co-transport,effective treatments to reduce blood phosphate, methods of treatinghyperphosphatemia, and methods of making inhibitors.

BACKGROUND OF THE INVENTION

Secondary hyperparathyroidism is a common and severe complication ofchronic renal failure (CRF) resulting in renal osteodystrophy,hypertension, metabolic acidosis, and contributing to cardiac disease.Hyperphosphatemia due to decreased renal phosphate excretion is thoughtto contribute to secondary hyperparathyroidism in patients with chronicrenal insufficiency. Recently, it has been established that decreasingthe phosphate load can reduce secondary hyperparathyroidism and possiblypreserve renal function.

In mammals, intestinal phosphate absorption occurs at the brush bordermembrane in the proximal intestine (duodenum and jejunum). Phosphateabsorption has an active component and a passive component. Activeuptake of phosphate is coupled to Na⁺ uptake down its electrochemicalpotential gradient by the Na⁺/phosphate cotransporter. The activecomponent of phosphate absorption is regulated by dietary phosphorus andserum 1,25 dihydroxyvitamin D₃. Changes in dietary phosphorus have beenreported to alter expression of NaPi II b in the intestine.Na⁺-independent phosphate uptake occurs by an unknown mechanism down itselectrochemical potential gradient. The mechanism of phosphate transportacross the intestinal basolateral membrane has not been defined

Chalcones are a class of aromatic ketones with important biologicalactivity and their effect on membrane transport is well known.Phloridzin, a member of the chalcones, is a potent inhibitor of therenal and intestinal brush border membrane Na⁺/glucose cotransporters.The aglucone of phloridzin, phloretin, inhibits a variety of membranetransporters including Band 3 (AE-1, 9, 10) and the facilitateddiffusion glucose carrier (GLUT-4, 9, 14). A phosphorylated phloretinderivative, 2′-PP, has been shown to be a potent inhibitor of theintestinal Na⁺/phosphate cotransporter but not the primary renalproximal tubule Na⁺/phosphate cotransporter. The major limitation of2′-PP for the treatment of hyperphosphatemia is that it is a phosphateester, and therefore, it is degraded by phosphatases, including theintestinal apical membrane phosphatase, alkaline phosphatase.

Thus, new or improved agents which inhibit intestinal apical membraneNa⁺-mediated phosphate co-transport are continually needed fordeveloping new and more effective pharmaceuticals that are aimed at thetreatment of secondary hyperparathyroidism caused by CRF and resultingin renal osteodystrophy, hypertension, metabolic acidosis, andcontributing to cardiac disease. 2′-FPP which is 30 times more potentthan 2′-PP and is also more stable to esterases represents a majoradvance and improvement over 2′-PP well known to be efficacious in thetreatment of CRF. The compounds, compositions and methods describedherein are directed toward these needs and other ends.

SUMMARY OF THE INVENTION

The present invention provides, inter alia, compounds conforming toFormula I:

or a pharmaceutically acceptable salt thereof, wherein constituentmembers are defined herein. The compounds can inhibit intestinal apicalmembrane sodium-mediated phosphate co-transport.

The present invention further provides pharmaceutical compositionscomprising a compound of Formula I, or a pharmaceutically acceptablesalt thereof, and at least one pharmaceutically acceptable carrier. Thecompound can be present in an amount that confers a clinicallybeneficial result on a patient to whom the compound has beenadministered. Thus, the compositions can include therapeuticallyeffective amounts of the compounds described herein.

The present invention further provides methods of inhibiting intestinalapical sodium/phosphate cotransport, comprising contacting theintestinal epithelium with a compound of Formula I, or apharmaceutically acceptable salt thereof.

The present invention further provides methods of treating a disease ora disorder associated with abnormal blood phosphate levels in a patientby administering to a patient a therapeutically effective amount of acompound of Formula I, or a pharmaceutically acceptable salt of thesame.

The present invention further provides methods of treating diseases suchas chronic renal failure, renal osteodystrophy, hypertension, metabolicacidosis, and cardiac disease in a patient by administering to thepatient a compound of Formula I, or a pharmaceutically acceptable saltthereof. The renal failure can be end-stage renal failure.

The present invention further provides a compound of Formula I, or apharmaceutically acceptable salt thereof, for use in the preparation ofa medicament or for the production of a medicament for use in therapy,including therapy for a condition described herein.

The present invention provides processes for preparing a compound ofFormula I:

or a pharmaceutically acceptable salt thereof, wherein R is C₂₋₄ alkyl;W is selected from NR^(A), O, and S; Z is selected from a single bond,—C(O)—, NR^(A), O, and S; X¹ and X² are each independently selected from—OH, —NHR^(A), and —C(O)OH; R^(A) is H or C₁₋₃ alkyl; m is 1, 2, 3, or4; and n is 1, 2, 3, or 4.

The present invention provides processes for preparing a compound ofFormula I-1:

The present invention provides processes for preparing a compound ofFormula I-2:

The present invention provides processes for preparing a compound ofFormula I-3:

The present invention provides processes for preparing a compound ofFormula I-4:

DETAILED DESCRIPTION

The present invention provides, inter alia, compounds that inhibitapical Na/phosphate cotransport and are useful, for example, to reduceblood phosphate levels, and in the treatment of hyperphosphatemia. Thecompounds of the invention include those having Formula I:

or a pharmaceutically acceptable salt thereof, wherein:

R is C₂₋₄ alkyl;

W is selected from NR^(A), O, and S;

Z is selected from a single bond, —C(O)—, NR^(A), O, and S;

X¹ and X² are each independently selected from —OH, —NHR^(A), and—C(O)OH;

R^(A) is H or C₁₋₃ alkyl;

m is 1, 2, 3, or 4; and

n is 1, 2, 3, or 4.

In other embodiments, X¹ and X² are each independently selected from OR¹and OR², wherein R¹ and R² are independently H or a protecting group. Inother embodiments, X¹ and X² are independently selected from COOR¹ andCOOR², wherein R¹ and R² are independently H or a protecting group.

In some embodiments, R is —CH₂—CH₂— or —CH₂—CH₂—CH₂—.

In some embodiments, W is selected from NR^(A) and O.

In some embodiments, W is O.

In some embodiments, Z is selected from a single bond and —C(O)—.

In some embodiments, Z is —C(O)—.

In some embodiments, X¹ and X² are independently selected from OH andNH₂.

In some embodiments, X¹ and X² are both OH.

In some embodiments, n is 1 or 2.

In some embodiments, m is 1 or 2.

In some embodiments, m is 2 and n is 1.

In some embodiments, R is —CH₂—CH₂— and Z is —C(O)—.

In some embodiments, W is O, and X¹ and X² are both OH.

As used herein, the term “alkyl” is meant to refer to a saturatedhydrocarbon group which is straight-chained or branched. Example alkylgroups include methyl (Me), ethyl (Et), propyl (e.g., n-propyl andisopropyl), butyl (e.g., n-butyl, isobutyl, sec-butyl, t-butyl), pentyl(e.g., n-pentyl, isopentyl, sec-pentyl, neopentyl), and the like. Analkyl group can contain from 1 to about 20, from 2 to about 20, from 1to about 10, from 1 to about 8, from 1 to about 6, from 1 to about 4, orfrom 1 to about 3 carbon atoms.

As used herein, “aryl” refers to monocyclic or polycyclic (e.g., having2, 3 or 4 fused rings) aromatic hydrocarbons such as, for example,phenyl, naphthyl, anthracenyl, phenanthrenyl, indanyl, indenyl, and thelike. In some embodiments, aryl groups have from 6 to about 20 carbonatoms.

As used herein, “heteroaryl” refers to an aromatic heterocycle having atleast one heteroatom ring member such as sulfur, oxygen, or nitrogen.Heteroaryl groups include monocyclic and polycyclic (e.g., having 2, 3or 4 fused rings) systems. Examples of heteroaryl groups include withoutlimitation, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl,furyl, quinolyl, isoquinolyl, thienyl, imidazolyl, thiazolyl, indolyl,pyrryl, oxazolyl, benzofuryl, benzothienyl, benzthiazolyl, isoxazolyl,pyrazolyl, triazolyl, tetrazolyl, indazolyl, 1,2,4-thiadiazolyl,isothiazolyl, benzothienyl, purinyl, carbazolyl, benzimidazolyl,indolinyl, and the like. Examples of bicyclic heteroaryl groups includewithout limitation, purinyl, indolyl, and the like. In some embodiments,any ring-forming N in a heteroaryl moiety can be substituted by oxo. Insome embodiments, the heteroaryl group has from 1 to about 20 carbonatoms, and in further embodiments from about 3 to about 20 carbon atoms.In some embodiments, the heteroaryl group contains 3 to about 14, 4 toabout 14, 9 to about 10, or 5 to 6 ring-forming atoms. In someembodiments, the heteroaryl group has 1 to about 4, 1 to about 3, or 1to 2 heteroatoms.

It should be further appreciated that certain features of the invention,which are, for clarity, described in the context of separateembodiments, can also be provided in combination in a single embodiment.Conversely, various features of the invention which are, for brevity,described in the context of a single embodiment, can also be providedseparately or in any suitable subcombination.

The compounds described herein can be asymmetric (e.g., having one ormore stereocenters). All stereoisomers, such as enantiomers anddiastereomers, are intended unless otherwise indicated. Compounds of thepresent invention that contain asymmetrically substituted carbon atomscan be isolated in optically active or racemic forms. Methods on how toprepare optically active forms from optically inactive startingmaterials are known in the art, such as by resolution of racemicmixtures or by stereoselective synthesis. Many geometric isomers ofolefins, C═N double bonds, and the like can also be present in thecompounds described herein, and all such stable isomers are contemplatedin the present invention. Cis and trans geometric isomers of thecompounds of the present invention are described and may be isolated asa mixture of isomers or as separated isomeric forms.

Resolution of racemic mixtures of compounds can be carried out by any ofnumerous methods known in the art. An example method includes fractionalrecrystallizaion using a chiral resolving acid which is an opticallyactive, salt-forming organic acid. Suitable resolving agents forfractional recrystallization methods are, for example, optically activeacids, such as the D and L forms of tartaric acid, diacetyltartaricacid, dibenzoyltartaric acid, mandelic acid, malic acid, lactic acid orthe various optically active camphorsulfonic acids such asβ-camphorsulfonic acid. Other resolving agents suitable for fractionalcrystallization methods include stereoisomerically pure forms ofα-methylbenzylamine (e.g., S and R forms, or diastereomerically pureforms), 2-phenylglycinol, norephedrine, ephedrine, N-methylephedrine,cyclohexylethylamine, 1,2-diaminocyclohexane, and the like.

Resolution of racemic mixtures can also be carried out by elution on acolumn packed with an optically active resolving agent (e.g.,dinitrobenzoylphenylglycine). Suitable elution solvent composition canbe determined by one skilled in the art.

Compounds of the invention also include tautomeric forms. Tautomericforms result from the swapping of a single bond with an adjacent doublebond together with the concomitant migration of a proton. Tautomericforms include prototropic tautomers which are isomeric protonationstates having the same empirical formula and total charge. Exampleprototropic tautomers include ketone-enol pairs, amide-imidic acidpairs, lactam-lactim pairs, amide-imidic acid pairs, enamine-iminepairs, and annular forms where a proton can occupy two or more positionsof a heterocyclic system, for example, 1H- and 3H-imidazole, 1H-, 2H-and 4H-1,2,4-triazole, 1H- and 2H-isoindole, and 1H- and 2H-pyrazole.Tautomeric forms can be in equilibrium or sterically locked into oneform by appropriate substitution.

Compounds of the invention can also include all isotopes of atomsoccurring in the intermediates or final compounds. Isotopes includethose atoms having the same atomic number but different mass numbers.For example, isotopes of hydrogen include tritium and deuterium.

The term, “compound,” as used herein is meant to include allstereoisomers, geometric isomers, tautomers, and isotopes of thestructures depicted, including structures conforming to a genericformula set out herein.

All compounds, and pharmaceutically acceptable salts thereof, can befound together with other substances such as water and solvents (e.g.hydrates and solvates) or can be isolated.

In some embodiments, the compounds of the invention, or salts thereof,are substantially isolated. By “substantially isolated” is meant thatthe compound is at least partially or substantially separated from theenvironment in which it was formed or detected. Partial separation caninclude, for example, a composition enriched in the compounds of theinvention. Substantial separation can include compositions containing atleast about 50%, at least about 60%, at least about 70%, at least about80%, at least about 90%, at least about 95%, at least about 97%, or atleast about 99% by weight of the compounds of the invention, or saltthereof. Methods for isolating compounds and their salts are routine inthe art.

The phrase “pharmaceutically acceptable” is employed herein to refer tothose compounds, materials, compositions, and/or dosage forms which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of human beings and animals without excessive toxicity,irritation, allergic response, or other problem or complication,commensurate with a reasonable benefit/risk ratio.

The expressions, “ambient temperature” and “room temperature,” as usedherein, are understood in the art, and refer generally to a temperature,e.g. a reaction temperature, that is about the temperature of the roomin which the reaction is carried out, for example, a temperature fromabout 20° C. to about 30° C.

The present invention also includes pharmaceutically acceptable salts ofthe compounds described herein. As used herein, “pharmaceuticallyacceptable salts” refers to derivatives of the disclosed compoundswherein the parent compound is modified by converting an existing acidor base moiety to its salt form. Examples of pharmaceutically acceptablesalts include, but are not limited to, mineral or organic acid salts ofbasic residues such as amines; alkali or organic salts of acidicresidues such as carboxylic acids; and the like. The pharmaceuticallyacceptable salts of the present invention include the conventionalnon-toxic salts of the parent compound formed, for example, fromnon-toxic inorganic or organic acids. The pharmaceutically acceptablesalts of the present invention can be synthesized from the parentcompound which contains a basic or acidic moiety by conventionalchemical methods. Generally, such salts can be prepared by reacting thefree acid or base forms of these compounds with a stoichiometric amountof the appropriate base or acid in water or in an organic solvent, or ina mixture of the two; generally, non-aqueous media like ether, ethylacetate, alcohols (e.g., methanol, ethanol, iso-propanol, or butanol) oracetonitrile (ACN) are preferred. Lists of suitable salts are found inRemington's Pharmaceutical Sciences, 17th ed., Mack Publishing Company,Easton, Pa., 1985, p. 1418 and Journal of Pharmaceutical Science, 66, 2(1977), each of which is incorporated herein by reference in itsentirety.

Synthesis:

The processes and intermediates of the present invention are useful inthe preparation of inhibitors of intestinal apical sodium/phosphatecotransport, effective in reducing blood phosphate levels andhyperphosphatemia. Compounds of the invention, including salts thereof,can be prepared using known organic synthesis techniques and can besynthesized according to any of numerous possible synthetic routes.

The reactions for preparing compounds of the invention can be carriedout in suitable solvents which can be readily selected by one of skillin the art of organic synthesis. Suitable solvents can be substantiallynon-reactive with the starting materials (reactants), the intermediates,or products at the temperatures at which the reactions are carried out,e.g., temperatures which can range from the solvent's freezingtemperature to the solvent's boiling temperature. A given reaction canbe carried out in one solvent or a mixture of more than one solvent.Depending on the particular reaction step, suitable solvents for aparticular reaction step can be selected by the skilled artisan.

Preparation of compounds of the invention can involve the protection anddeprotection of various chemical groups. The need for protection anddeprotection, and the selection of appropriate protecting groups, can bereadily determined by one skilled in the art. The chemistry ofprotecting groups can be found, for example, in T. W. Greene and P. G.M. Wuts, Protective Groups in Organic Synthesis, 3^(rd) Ed., Wiley &Sons, Inc., New York (1999), which is incorporated herein by referencein its entirety.

Reactions can be monitored according to any suitable method known in theart. For example, product formation can be monitored by spectroscopicmeans, such as nuclear magnetic resonance spectroscopy (e.g., ¹H or¹³C), infrared spectroscopy, spectrophotometry (e.g., UV-visible), massspectrometry, or by chromatographic methods such as high performanceliquid chromatography (HPLC) or thin layer chromatography (TLC).

Example synthetic methods for preparing compounds of the invention areprovided in the Schemes below. For instance, compounds of the inventioncan be prepared by the general retrosynthetic scheme shown in Scheme 1.Compounds of formula 1 can be prepared by subjecting a compound offormula 2 with a fluorinating agent. Compounds of formula 2 can besynthesized by removing Pr² from a compound of formula 3. Compounds offormula 3 can be readily prepared from the phosphorylation of compoundsof formula 4. Finally, compounds of formula 5 can be synthesized via theselective deprotection revealing the attachment point (W) forphosphorylation.

Accordingly, the present invention provides a process for preparing acompound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein R is C₂₋₄ alkyl;

W is selected from NR^(A), O, and S; Z is selected from a single bond,—C(O)—, NR^(A), O, and S; X¹ and X² are each independently selected from—OH, —NHR^(A), and —C(O)OH; R^(A) is H or C₁₋₃ alkyl; m is 1, 2, 3, or4; and n is 1, 2, 3, or 4;

the process comprising:

a) removing Pr¹ in the presence of Pr² from a compound of Formula I-1:

wherein Pr¹ and Pr² are protecting groups; to prepare a compound ofFormula I-2:

b) reacting a compound of Formula I-2 with a phosphorylating agent toprepare a compound of Formula I-3:

c) removing Pr² from a compound of Formula I-3 with a reducing agent toprepare a compound of Formula I-4:

d) reacting a compound of Formula I-4 with a fluorinating agent toprepare said compound of Formula I.

In some embodiments, Pr¹ is:

In some embodiments, Pr² is benzyl.

In some embodiments, the phosphorylating agent is a phosphite ester. Ina further embodiment, the phosphite ester is dibenzyl phosphite. Inanother embodiment, the phosphorylating agent is a phosphonic acid. In afurther embodiment, the phosphonic acid is fluorophosphonic acid.

In some embodiments, the reducing agent is comprised of hydrogen gas anda transition metal.

In some embodiments, the fluorinating agent is dinitrofluorobenzene. Ina further embodiment, the fluorinating agent is hydrofluoric acid.

As shown in Scheme 2, the known compound phloridzin is benzylated toprovide the fully benzyl-protected compound 6. Treatment of compound 6under acidic conditions provided phenol 7 which was converted into thebenzyl-protected phosphate compound 8. Catalytic hydrogenation of 8provided 2′-phosphophloretin (9) which was fluorinated with afluorinating agent such as dinitrofluorobenzene (DNFB) or hydrofluoricacid (HF) to provide 2′-fluorophosphophloretin (10).

Alternatively, 2′ phosphophloretin (9) can be fluorinated usinganhydrous hydrofluoric acid to yield 2′-fluorophosphophloretin (10)(Scheme 3).

An alternative route to preparing 2′-fluorophosphophloretin is shown inScheme 4 starting from the known compound phloridzin. Benzylation ofphloridzin provided 6 which was selectively deprotected to provide thephenol 7. Treatment with dichlorochromate (DCC) and fluorophosphonicacid afforded the fluorophosphonic acid 8a. Removal of the benzyl groupsof 8a was accomplished using ammonium and Dowex 50W to provide2′-fluorophosphophloretin.

Methods of Use:

Compounds of the invention can inhibit intestinal apicalsodium/phosphate co-transport. Compounds of the invention can also be aneffective treatment to reduce blood phosphate levels andhyperphosphatemia.

The present invention further provides methods for treating a diseasecaused by or associated with elevated blood phosphate levels in amammalian subject, including identifying a subject in which reduction ofblood phosphate levels is desirable, and administering to the subject inneed of such treatment a therapeutically effective amount or dose of acompound of the present invention or a pharmaceutical compositionthereof. In some embodiments, the subject is a mammal. In someembodiments, the subject is a human. In some embodiments, the compoundis administered orally. In some embodiments, the disease is chronicrenal failure. In some embodiments, chronic renal failure is associatedwith and/or accompanied by hyperphosphatemia, secondaryhyperparathyroidism, renal osteodystrophy, hypertension, metabolicacidosis, or cardiac disease. The chronic renal failure may be end-stagerenal failure, and patients suffering from end-stage renal failure areamenable to treatment as described herein.

As used herein, the term “contacting” refers to the bringing together ofindicated moieties in an in vitro system or an in vivo system. Forexample, “contacting” a compound of the invention with the intestinalapical sodium/phosphate co-transport includes the administration of acompound of the present invention to an individual or patient, such as ahuman, as well as, for example, introducing a compound of the inventioninto a sample containing a cellular or purified preparation of theintestinal apical sodium/phosphate co-transport.

As used herein, the term “individual” or “patient,” usedinterchangeably, refers to any animal, including mammals, preferablymice, rats, other rodents, rabbits, dogs, cats, swine, cattle, sheep,horses, or primates, and most preferably humans.

As used herein, the phrase “therapeutically effective amount” refers tothe amount of active compound or pharmaceutical agent that elicits thebiological or medicinal response that is being sought in a tissue,system, animal, individual or human by a researcher, veterinarian,medical doctor or other clinician.

As used herein, the term “treating” or “treatment” refers to one or moreof (1) preventing the disease; for example, preventing a disease,condition or disorder in an individual who may be predisposed to thedisease, condition or disorder but does not yet experience or displaythe pathology or symptomatology of the disease; (2) inhibiting thedisease; for example, inhibiting a disease, condition or disorder in anindividual who is experiencing or displaying the pathology orsymptomatology of the disease, condition or disorder; and (3)ameliorating the disease; for example, ameliorating a disease, conditionor disorder in an individual who is experiencing or displaying thepathology or symptomatology of the disease, condition or disorder (i.e.,reversing the pathology and/or symptomatology) such as decreasing theseverity of disease.

Pharmaceutical Formulations and Dosage Forms:

When employed as pharmaceuticals, the compounds of the invention can beadministered in the form of pharmaceutical compositions. Thesecompositions can be prepared in a manner well known in thepharmaceutical art, and can be administered by a variety of routes,depending upon whether local or systemic treatment is desired and uponthe area to be treated. Administration may be oral.

This invention also includes pharmaceutical compositions which contain,as the active ingredient, the compound of the invention or apharmaceutically acceptable salt thereof, in combination with one ormore pharmaceutically acceptable carriers (excipients). In someembodiments, the composition is suitable for oral administration. Inmaking the compositions of the invention, the active ingredient istypically mixed with an excipient, diluted by an excipient or enclosedwithin such a carrier in the form of, for example, a capsule, sachet,paper, or other container. When the excipient serves as a diluent, itcan be a solid, semi-solid, or liquid material, which acts as a vehicle,carrier or medium for the active ingredient. Thus, the compositions canbe in the form of tablets, pills, powders, lozenges, sachets, cachets,elixirs, suspensions, emulsions, solutions, syrups, soft and hardgelatin capsules, and sterile packaged powders.

In preparing a formulation, the active compound can be milled to providethe appropriate particle size prior to combining with the otheringredients. If the active compound is substantially insoluble, it canbe milled to a particle size of less than 200 mesh. If the activecompound is substantially water soluble, the particle size can beadjusted by milling to provide a substantially uniform distribution inthe formulation, e.g. about 40 mesh.

The compounds of the invention may be milled using known millingprocedures such as wet milling to obtain a particle size appropriate fortablet formation and for other formulation types. Finely divided(nanoparticulate) preparations of the compounds of the invention can beprepared by processes known in the art, e.g., see International App. No.WO 2002/000196.

Some examples of suitable excipients include lactose, dextrose, sucrose,sorbitol, mannitol, starches, gum acacia, calcium phosphate, alginates,tragacanth, gelatin, calcium silicate, microcrystalline cellulose,polyvinylpyrrolidone, cellulose, water, syrup, and methyl cellulose. Theformulations can additionally include: lubricating agents such as talc,magnesium stearate, and mineral oil; wetting agents; emulsifying andsuspending agents; preserving agents such as methyl- andpropylhydroxy-benzoates; sweetening agents; and flavoring agents. Thecompositions of the invention can be formulated so as to provide quick,sustained or delayed release of the active ingredient afteradministration to the patient by employing procedures known in the art.

The compositions can be formulated in a unit dosage form, each dosagecontaining from about 5 to about 1000 mg (1 g), more usually about 100to about 500 mg, of the active ingredient. The term “unit dosage forms”refers to physically discrete units suitable as unitary dosages forhuman subjects and other mammals, each unit containing a predeterminedquantity of active material calculated to produce the desiredtherapeutic effect, in association with a suitable pharmaceuticalexcipient.

In some embodiments, the compounds or compositions of the inventioncontain from about 5 to about 50 mg of the active ingredient. One havingordinary skill in the art will appreciate that this embodies compoundsor compositions containing about 5 to about 10, about 10 to about 15,about 15 to about 20, about 20 to about 25, about 25 to about 30, about30 to about 35, about 35 to about 40, about 40 to about 45, or about 45to about 50 mg of the active ingredient.

In some embodiments, the compounds or compositions of the inventioncontain from about 50 to about 500 mg of the active ingredient. Onehaving ordinary skill in the art will appreciate that this embodiescompounds or compositions containing about 50 to about 100, about 100 toabout 150, about 150 to about 200, about 200 to about 250, about 250 toabout 300, about 350 to about 400, or about 450 to about 500 mg of theactive ingredient.

In some embodiments, the compounds or compositions of the inventioncontain from about 500 to about 1000 mg of the active ingredient. Onehaving ordinary skill in the art will appreciate that this embodiescompounds or compositions containing about 500 to about 550, about 550to about 600, about 600 to about 650, about 650 to about 700, about 700to about 750, about 750 to about 800, about 800 to about 850, about 850to about 900, about 900 to about 950, or about 950 to about 1000 mg ofthe active ingredient.

The active compound can be effective over a wide dosage range and isgenerally administered in a pharmaceutically effective amount. It willbe understood, however, that the amount of the compound actuallyadministered will usually be determined by a physician, according to therelevant circumstances, including the condition to be treated, thechosen route of administration, the actual compound administered, theage, weight, and response of the individual patient, the severity of thepatient's symptoms, and the like.

For preparing solid compositions such as tablets, the principal activeingredient is mixed with a pharmaceutical excipient to form a solidpreformulation composition containing a homogeneous mixture of acompound of the present invention. When referring to thesepreformulation compositions as homogeneous, the active ingredient istypically dispersed evenly throughout the composition so that thecomposition can be readily subdivided into equally effective unit dosageforms such as tablets, pills and capsules. This solid preformulation isthen subdivided into unit dosage forms of the type described abovecontaining from, for example, about 0.1 to about 1000 mg of the activeingredient of the present invention.

The tablets or pills of the present invention can be coated or otherwisecompounded to provide a dosage form affording the advantage of prolongedaction. For example, the tablet or pill can comprise an inner dosage andan outer dosage component, the latter being in the form of an envelopeover the former. The two components can be separated by an enteric layerwhich serves to resist disintegration in the stomach and permit theinner component to pass intact into the duodenum or to be delayed inrelease. A variety of materials can be used for such enteric layers orcoatings, such materials including a number of polymeric acids andmixtures of polymeric acids with such materials as shellac, cetylalcohol, and cellulose acetate.

The liquid forms in which the compounds and compositions of the presentinvention can be incorporated for administration orally or by injectioninclude aqueous solutions, suitably flavored syrups, aqueous or oilsuspensions, and flavored emulsions with edible oils such as cottonseedoil, sesame oil, coconut oil, or peanut oil, as well as elixirs andsimilar pharmaceutical vehicles.

In some embodiments, the compositions are administered by the oral routefor local effect. Solution, suspension, or powder compositions can beadministered orally from devices which deliver the formulation in anappropriate manner.

The amount of compound or composition administered to a patient willvary depending upon what is being administered, the purpose of theadministration, such as prophylaxis or therapy, the state of thepatient, the manner of administration, and the like. In therapeuticapplications, compositions can be administered to a patient alreadysuffering from a disease in an amount sufficient to cure or at leastpartially arrest the symptoms of the disease and its complications.Effective doses will depend on the disease condition being treated aswell as by the judgment of the attending clinician depending uponfactors such as the severity of the disease, the age, weight and generalcondition of the patient, and the like.

The compositions administered to a patient can be in the form ofpharmaceutical compositions described above. These compositions can besterilized by conventional sterilization techniques, or may be sterilefiltered. Aqueous solutions can be packaged for use as is, orlyophilized, the lyophilized preparation being combined with a sterileaqueous carrier prior to administration. The pH of the compoundpreparations typically will be between 3 and 11, more preferably from 5to 9 and most preferably from 7 to 8. It will be understood that use ofcertain of the foregoing excipients, carriers, or stabilizers willresult in the formation of pharmaceutical salts.

The therapeutic dosage of a compound of the present invention can varyaccording to, for example, the particular use for which the treatment ismade, the manner of administration of the compound, the health andcondition of the patient, and the judgment of the prescribing physician.The proportion or concentration of a compound of the invention in apharmaceutical composition can vary depending upon a number of factorsincluding dosage, chemical characteristics (e.g., hydrophobicity), andthe route of administration. For example, the compounds of the inventioncan be provided in an aqueous physiological buffer solution containingabout 0.1 to about 10% w/v of the compound for parenteraladministration. Some typical dose ranges are from about 1 μg/kg to about1 g/kg of body weight per day.

In studies with 2′-phosphophoiretin, we administered to animals 0.1g/day and observed no side effects over a 3-month trial in normal or⅚^(th) nephrectomy rats. In other studies, with 2′-phosphofluorophloretin, we administered to animals 0.02 g/day. We observed no sideeffects over a 2-month trial in normal rats; over a 1-month trial in⅚^(th) nephrectomy rats; and over a 1-month trial in Dahl-salt sensitiverats. Our compounds compared favorably with calcium salts (such asTUMS®), LaCO₃ (FOSRENOL®), and a phosphorous binding resin (RENAGEL®).

In some embodiments, the dose range is from about 0.01 mg/kg to about100 mg/kg of body weight per day. The dosage is likely to depend on suchvariables as the type and extent of progression of the disease ordisorder, the overall health status of the particular patient, therelative biological efficacy of the compound selected, formulation ofthe excipient, and its route of administration. Effective doses can beextrapolated from dose-response curves derived from in vitro or animalmodel test systems.

EXAMPLES Example 1 Synthesis of 2′-fluorophosphophloretin (2′-FPP) usingDinitrofluorobenzene (DNFB)

2′-fluorophosphphloretin (2′-FPP) was synthesized according to themethod of Peerce et al. Am. J. Physiol. Gastrointest. Liver Physiol.283: G848-G855, 2002.

Step 1. 4,6,4-tri-O-benzylphloretin

Phloridzin (2 g) was dissolved in redistilled dimethylformamide (35 ml)and potassium carbonate (3.1 g). Benzylbromide (2.7 ml) was added tothis solution and the reaction mixture was allowed to stir for 3 days at23° C. The solution was distilled under vacuum, and the residue wascooled to room temperature. The residue was extracted with water/ethylacetate (2:1) three times. The organic layers were combined andconcentrated in vacuo. The residue was dissolved in 1,4 dioxane (200ml), and HCl was added dropwise to a final concentration of 0.4 N. Themixture was refluxed for 3 hours. The reaction mixture was cooled,diluted with 1 M sodium bicarbonate, and extracted with ethyl acetate.The ethyl acetate extraction was repeated three times. The combinedorganic extracts were washed with water, followed by two washes withNaCl (0.9%). Anhydrous Na₂SO₄ was added to the organic layer and mixed.Vacuum filtration removed the Na₂SO₄. Fresh Na₂SO₄ was added to thesolution, which was then stirred for 12 hours at 23° C. Vacuumfiltration removed the Na₂SO₄, and the filtrate was concentrated toyield 4,6,4-tri-O-benzylphloretin (2.1 g, 92% yield): ¹H-NMR (CDCl₃)δ13.6 (s, 1H); 7.46-7.29 (m, 15H); 6.86 (d, J=8.8 Hz, 2H); 6.8 (d, J=8.8Hz, 2H); 6.35 (d, J=2.3 Hz, 1H); 6.21 (d, J=2.3 Hz, 1H); 5.17 (s, 2H);5.14 (s, 2H); 5.07 (s, 2H); 3.2 (t, J=7.1 Hz, 2H) ppm.

Step 2. Dibenzylphosphotribenzyl phloretin

4,6,4-Tri-O-benzylphloretin (2.1 g) was dissolved inN,N-dimethylacetamide (DMAc) and placed on ice. Sodium hydride (60%) wasadded, and the mixture was stirred at 23° C. for 1 hour. The solutionwas cooled, and the sodium hydride was inactivated with carbontetrachloride. Dibenzylphosphite (1.31 ml) in N,N-dimethylacetamide wasadded, and the solution was stirred for 30 min. The solution wasacidified and partitioned between water and hexane/ethyl acetate (1:1).The water layer was extracted three times with hexane/ethyl acetate. Thecombined organic layers were washed with 0.9% NaCl and dried overanhydrous sodium sulfate. Sodium sulfate was removed by filtration. Thefiltrate was concentrated in vacuo and purified by chromatography onsilica gel using ethyl acetate/dichloromethane/hexanes (5:25:70) as theeluant. Dibenzylphosphotribenzyl phloretin (750 mg, 43% yield) wasrecovered: ¹H-NMR (CDCl₃) δ 7.42-7.29 (m, 25H); 6.93 (d, J=8.8 Hz, 2H);6.78 (d, J=8.8 Hz, 2H); 6.63 [double doublet (dd), J=1.2, 2 Hz, 1H]; 6.4(dd, J=0.6, 2.1 Hz, 1H); 5.06 (s, 5.04, 2H); 5.04 (s, 2H); 4.97 (d,J=4.8 Hz, 4H); 4.87 (s, 2H); 3.03 (t, J=8.4 Hz, 2H); 2.83 (t, J=8.2 Hz,2H) ppm.

Step 3. 2′-fluorophosphphloretin (2′-FPP)

Dibenzylphosphotribenzyl phloretin was dissolved in ethyl acetate.Palladium on carbon (200 mg of 10%) was added, and the solution wasstirred under H₂ gas for 2 hours. The solution was filtered throughCelite (Sigma-Aldrich). The Celite cake was washed twice with ethylacetate, and the combined washes were concentrated under reducedpressure to yield 2′-PP (400 mg, 29% yield) after drying: melting point(mp), 171-172° C., ¹H-NMR (d₆-DMSO) δ 13.0 (s, 1H); 10.7 (bs, 1H); 9.2(bs, 1H); 7.03 (d, J=8.6 Hz, 2H); 6.64 (d, J=8.4 Hz, 2H); 6.63 (dd,J=1.2, 2.1 Hz, 1H); 2.77 (d, J=7.6 Hz, 2H) ppm.

³¹P-NMR in D₂O yielded a single peak at 4 ppm composed of 98% of thephosphorus signal. ³¹P-NMR in DMSO yielded a single peak at 4.3pulses/min. H-decoupled ¹³C-NMR experiments gave 12 unique carbonspecies that could be assigned to the inhibitor.

Electrospray mass spectrometry gave a mass/ion charge of 355(mass+proton) consistent with the calculated molecular mass of 2′-PP of354.

2′-PP was passed through an ion exchange column equilibrated with 100 mMtetramethylammonium bicarbonate, concentrated under vacuum and added to10 mM DNFB. The reaction was stirred at 23° C. for 4 hours, and thereactants were washed through a silica gel column eluting withchloroform:methanol (70%:30%). Fractions were dried and precipitatedwith 0.1 M NaOH. The precipitate was collected, buffer exchanged througha Sephadex G-10 column and concentrated under vacuum.

Example 2 Synthesis of 2′-fluorophosphophloretin (2′-FPP) UsingHydrofluoric Acid

An alternative synthesis of 2′-FPP was performed substitutinghydrofluoric acid for DNFB.

Starting with 20 mg of 2′-PP dissolved in 1 ml. DMF, 0.1 ml of 0.1 M HFwas added and the solution allowed to sit at 23° C. for 2 hours. Thereaction mixture was cooled, and neutralized to pH 8 with 12 N NaOH. Theprecipitated products were passed through a Sephadex G-10 columnequilibrated with 100 mM TMAHCO₃ and lyophilized.

2′-FPP purity was examined by thin layer chromatography on silica gelusing chloroform:methanol (7:3), or chloroform:3-propanol (8:2).Analysis of 2′-FPP following TLC was performed by comparison byphloretin and 2′-PP. TLC plates were examined for phosphate byFiske-SubbaRow reaction and for fluoride with Zirconium-alizarin lakeHCl. A positive reaction with alizarin lake required heating the TLCstrip for 1 hour at 60° C. ¹H-NMR (d₆-DMSO) δ 10.7 (s, 1H); 9.3, (s,1H); 7.17 (t, 2H J=8.6 Hz), 6.8 (t, 2H); 6.6 (d, 2H, J=8.4 Hz), 3.2 (t,2H, J=2 Hz); 2.9 (t, 2H, J=2.1 Hz); 1.9 (weak singlet) ppm.

Example A Effects of 2′-FPP on Na-Dependent [³²P] Phosphate Uptake

The effect of 2′-FPP on Na-dependent [³²P] phosphate uptake intointestinal brush border membrane (apical) vesicles was examined usingrapid mixing rapid filtration experiments and liquid scintillationcounting of filter retained counts in the presence of 100 mM Na or 100mM K cis (inward) directed gradients. 2′-PP and 2′-FPP both inhibitedNa-dependent phosphate uptake into intestinal brush border membranevesicles. 2′-FPP was 12× more potent than 2′-PP in inhibitingNa-dependent phosphate uptake. The apparent IC₅₀ for 2′-PP was 46 nM±8nM (n=4) similar to previous results (Peerce et al., Biochem. Biophys.Res. Comm. 301:8-12, 2003; Peerce and Clarke, AM. J. Physiol.283:G848-G855, 2002). The IC₅₀ for 2′-FPP was 3.6 nM±0.6 nM (n=4).

Example B The Effect of Phosphophloretins on P-Nitrophosphate Hydrolysisby Rat Alkaline Phosphatase and Intestinal BBMV Phosphatases

The results shown in Example A used a 3-second exposure of vesicles andsubstrates and a 5 minute exposure of vesicles to 2′-FPP. Prior exposureand degradation of 2′-PP in contrast to 2′-FPP could be contributing tothe increased potency of 2′-FPP as compared to 2′-PP. To examine thispossibility the effect of phosphophloretins on p-nitrophosphatehydrolysis by rat alkaline phosphatase and intestinal BBMV phosphataseswas examined.

2′-PP is a better inhibitor of alkaline phosphatase activity andintestinal BBMV phosphatase activity than 2′-FPP. 2 mM 2′-PP resulted inapproximately 50% inhibition of intestinal BBMV phosphatase activity ascompared to less than 10% inhibition by 2′-FPP. Consistent with theinterpretation that the potency of 2′-PP as an inhibitor of Na-dependentphosphate uptake was limited by phosphatase mediated hydrolysis of2′-PP, addition of alkaline phosphatase inhibitors (ascorbicacid+cysteine) decreased the IC₅₀ for 2′-PP inhibition of Na-dependentphosphate uptake 34% (from 38 nM to 26 nM). These results indicate thatcompared to 2′-PP, 2 factors are responsible for the increased potencyof 2′-FPP as an inhibitor or Na-dependent phosphate uptake intointestinal brush border membrane vesicles: 1) increased resistance of2′-FPP to phosphatase catalyzed degradation of phosphate ester, and 2)increased affinity of fluorophosphates for the intestinal Na-phosphatecotransporter phosphate site compared to phosphate.

Example C Duration of Effect of a Single Exposure of Rat Intestine to2′-FPP and 2′-PP

To examine the duration of the effect of a single dose of 2′-FPP onphosphate uptake, intestinal strips were cut (approximately 5-cmsquares) and incubated in 12 well cell culture plates in the presence of2′FPP or 2′-PP for 1 hour, followed by exposure to fresh DMEM (Debecco'sModified Eagles Medium), [³²P] phosphate and varying concentrations of2′-PP or 2′-FPP.

A single exposure to 2′-PP resulted in greater than 60% inhibition ofphosphate uptake and that the inhibition was stable for 6 hourspost-drug exposure. In contrast exposure to 2′-PP resulted in 40%inhibition of phosphate uptake which decreased to less than 35%inhibition 6 hours post-drug exposure. Glucose uptake was unaffected byexposure to either 2′-PP or 2′-FPP consistent with previous reports thatphopshophloretins are specific for Na-phosphate cotransport, and thatintestinal strips were viable during the course of the experiment.

These experiments were expanded to examine the effect of 2′-FPPconcentration on phosphate uptake.

Rat duodenum/jejunum intestinal strips 1 cm square were incubated inDMEM at 37° C. and 5% CO₂ for one hour. After the incubation period, theDMEM was replaced containing 2′-FPP and the strips were incubated for anadditional hour. After the 1 hour exposure to 2′-FPP, DMEM was replacedwith fresh media +5 μCi of [³²P] phosphate. The strips were exposed totracer phosphate for 1 hour, precipitated with 10% TCA and centrifugedat 5000 g for 30 minutes. An aliquot of the supernatant was taken forscintillation counting.

Na-dependent phosphate uptake in the intestine is composed of bothNa-dependent and Na independent components. Na-dependent uptake intoduodenum and jejunum is approximately 70% Na-dependent and 30%Na-independent phosphate uptake. The results are consistent with 2′-FPPinhibiting the Na-dependent component which is driven by the intestinalbrush border membrane Na/phosphate cotransporter, NaPi 2b. Maximuminhibition was 67%±5% (n=4) of total phosphate absorption. The apparentIC₅₀ for 2′-FPP was 160 nM±20 nM (n=4). This compares with a maximuminhibition under identical conditions of 43±6% (n=3) for 2′-PP, and anIC₅₀ of 15 μM±3 μM (n=3).

Example D

The effect of 2′-FPP on serum phosphate and serum calcium in 4-5 monthold adult rats with normal renal function was examined. Rats weregavaged daily with 3 ml of 0.5 μM 2′-FPP in phosphate buffered saline pH7. Approximately 30 minutes later rats were exposed to food for 3 hours.After the feeding period, food was removed. Rats had ad libitum exposureto water. On the 3^(rd) day of the experiment, blood was drawn from thetail vein, prior to gavage. Animals were then gavaged as before, andexposed to food. This process was repeated on days 5, 8, 11, and 14. Onday 14 animal were sacrificed and the experiment terminated. Serumphosphorus, calcium, and BUN were determine using clinical kits.

Serum phosphorus decreased 52%±6% (n=8) in adult rats with normal renalfunction within the first week of treatment with 2′-FPP and remainstable at 3 mg/dL for the remainder of the 2-week experiment. Serum Ca²⁺was unaffected by 2′-FPP decreasing less than 2.5% during the 2-weekexposure to 2′-FPP. BUN was 10 mg/dl at the start of the experiment anddid not change over the course of the experiment. Previous experimentsunder identical conditions performed with 25 μM 2′-PP resulted in a30%±4% decrease in serum phosphorus with no change in serum Ca²⁺.

1. A compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein: R is C₂₋₄ alkyl;W is selected from NR^(A), O, and S; Z is selected from a single bond,—C(O)—, NR^(A), O, and S; X¹ and X² are each independently selected from—OH, —NHR^(A), and —C(O)OH; R^(A) is H or C₁₋₃ alkyl; m is 1, 2, 3, or4; and n is 1, 2, 3, or
 4. 2. The compound of claim 1, or apharmaceutically acceptable salt thereof, wherein R is —CH₂—CH₂— or—CH₂—CH₂—CH₂—.
 3. The compound of claim 1, or a pharmaceuticallyacceptable salt thereof, wherein W is selected from NR^(A) and O.
 4. Thecompound of claim 1, or a pharmaceutically acceptable salt thereof,wherein W is O.
 5. The compound of claim 1, or a pharmaceuticallyacceptable salt thereof, wherein Z is selected from a single bond and—C(O)—.
 6. The compound of claim 1, or a pharmaceutically acceptablesalt thereof, wherein Z is —C(O)—.
 7. The compound of claim 1, or apharmaceutically acceptable salt thereof, wherein X¹ and X² areindependently selected from OH and NH₂.
 8. The compound of claim 1, or apharmaceutically acceptable salt thereof, wherein X¹ and X² are both OH.9. The compound of claim 1, or a pharmaceutically acceptable saltthereof, wherein n is 1 or
 2. 10. The compound of claim 1, or apharmaceutically acceptable salt thereof, wherein m is 1 or
 2. 11. Thecompound of claim 1, or a pharmaceutically acceptable salt thereof,wherein m is 2 and n is
 1. 12. The compound of claim 1, or apharmaceutically acceptable salt thereof, wherein R is —CH₂—CH₂— and Zis —C(O)—.
 13. The compound of claim 1, or a pharmaceutically acceptablesalt thereof, wherein W is O, and X¹ and X² are both OH.
 14. A compoundof claim 1, or a pharmaceutically acceptable salt thereof, wherein thecompound is:


15. A compound of claim 1, wherein the compound is:


16. A composition comprising a compound of claim 1, or apharmaceutically acceptable salt thereof, and at least onepharmaceutically acceptable carrier.
 17. A method for treating a diseasecaused by or associated with elevated blood phosphate levels in amammalian subject, the method comprising identifying a subject in whichreduction of blood phosphate levels is desirable; and administering tothe subject a therapeutically effective amount of a compound of FormulaI:

18.-20. (canceled)
 21. The method of claim 17, wherein the compoundadministered is:

or a pharmaceutically acceptable salt thereof.
 22. A method for treatinga disease caused by or associated with elevated blood phosphate levelsin a patient in need thereof, the method comprising administering tosaid patient a therapeutically effective amount of a compound orcomposition of claim
 1. 23. The method of claim 22 wherein said diseaseis chronic renal failure.
 24. (canceled)
 25. The method of claim 22,wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 26. A process forpreparing a compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein R is C₂₋₄ alkyl;W is selected from NR^(A), O, and S; Z is selected from a single bond,—C(O)—, NR^(A), O, and S; X¹ and X² are each independently selected from—OH, —NHR^(A), and —C(O)OH; R^(A) is H or C₁₋₃ alkyl; m is 1, 2, 3, or4; and n is 1, 2, 3, or 4; the process comprising: a) removing Pr¹ inthe presence of Pr² from a compound of Formula I-1:

wherein Pr¹ and Pr² are protecting groups; to prepare a compound ofFormula I-2:

b) reacting a compound of Formula I-2 with a phosphorylating agent toprepare a compound of Formula I-3:

c) removing Pr² from a compound of Formula I-3 with a reducing agent toprepare a compound of Formula I-4:

d) reacting a compound of Formula I-4 with a fluorinating agent toprepare said compound of Formula I. 27.-35. (canceled)